(i) white phosphorus (ii) red phosporus and (iii) balck phosphorus. Write the difference between white red and black phosphorus on the basis of their structure and reactivity.
Phosphorus has three allotropic forms __

Explanation

Structrue. White phosphorus consists of discrete `P_(4)` molecules in which each P is `sp^(3)`-hybridized and lies at the corner of a tetrahedron. Thus, it has a tetrahedral structure with six P-P bonds
In contrast, red phosphorus also consists of `P_(4)` tetrahedra but these are joined together through single covalent P-P bonds to form a polymeric structure
Reactivity. White phosphours is much more reactive than red phosphorus. This is due to the reason that in white phosphours, the PPP angle is only `60^(@)` which is much smaller than the tetrahdral angle `(109^(@)-28^(@))`. As a result, `P_(4)` tetrahedral molecules have considerable angle strain and hence white P is very reactive. it readily catches fire in air. Becaues of polymeric structure, red P is however, much less reactive than white P. It is quite stable and does not catch fire in air.